Heater



FIG. 1 is a perspective view of a heater, showing my new design;

FIG. 2 is another perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The broken lines in the figures are for the purpose of illustrating portions of the heater that form no part of the claimed design. 

CLAIM The ornamental design for a heater, as shown and described. 